Add Epistemic Governance discourse event lane

[mdheller]

Context

SocioSphere PR #322 registers Epistemic Governance v0.2.1 and assigns SourceOS the local-first event integrity surface for discourse, repair, audit, tombstone, and replay state.

Required work

Add SourceOS event support for Epistemic Governance:

• schemas/sourceos.discourse-event.v0.1.schema.json
• schemas/sourceos.claim-repair-event.v0.1.schema.json
• schemas/sourceos.epistemic-audit-event.v0.1.schema.json
• examples/events/discourse/
• examples/events/claim-repair/

Lane mapping

• normal lane: claim parsed/classified and discourse graph deltas
• audit lane: audit append events
• policy lane: governance and policy decisions
• repair lane: claim repair and appeal correction events
• memory lane: accepted/canonized claim summaries
• tombstone lane: deleted, redacted, deprecated, or reversed events
• archive lane: export bundles and replay manifests
• secure lane: sensitive raw text and identity-linked records

Acceptance criteria

• sourceos_eventctl can validate and explain a discourse event.
• Append-only store write works for at least one discourse event.
• Store verification catches a tampered event.
• Event examples preserve privacy tier, lane, policy context, and replay relationship.

Upstream anchor

SocioSphere PR #322: Add Epistemic Governance standard and estate ownership map